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 * Copyright (c) 2014, Oracle America, Inc.

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 *    this list of conditions and the following disclaimer.

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 *    notice, this list of conditions and the following disclaimer in the

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 *    to endorse or promote products derived from this software without

 *    specific prior written permission.

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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

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package org.openjdk.jmh.samples;


import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.infra.Blackhole;

import org.openjdk.jmh.runner.Runner;

import org.openjdk.jmh.runner.RunnerException;

import org.openjdk.jmh.runner.options.Options;

import org.openjdk.jmh.runner.options.OptionsBuilder;


import java.util.concurrent.TimeUnit;


@BenchmarkMode(Mode.AverageTime)

@OutputTimeUnit(TimeUnit.NANOSECONDS)

public class JMHSample_21_ConsumeCPU {


 /*

  * At times you require the test to burn some of the cycles doing nothing.

  * In many cases, you *do* want to burn the cycles instead of waiting.

  *

  * For these occasions, we have the infrastructure support. Blackholes

  * can not only consume the values, but also the time! Run this test

  * to get familiar with this part of JMH.

  *

  * (Note we use static method because most of the use cases are deep

  * within the testing code, and propagating blackholes is tedious).

  */


 @Benchmark

 public void consume_0000() {

  Blackhole.consumeCPU(0);

 }


 @Benchmark

 public void consume_0001() {

  Blackhole.consumeCPU(1);

 }


 @Benchmark

 public void consume_0002() {

  Blackhole.consumeCPU(2);

 }


 @Benchmark

 public void consume_0004() {

  Blackhole.consumeCPU(4);

 }


 @Benchmark

 public void consume_0008() {

  Blackhole.consumeCPU(8);

 }


 @Benchmark

 public void consume_0016() {

  Blackhole.consumeCPU(16);

 }


 @Benchmark

 public void consume_0032() {

  Blackhole.consumeCPU(32);

 }


 @Benchmark

 public void consume_0064() {

  Blackhole.consumeCPU(64);

 }


 @Benchmark

 public void consume_0128() {

  Blackhole.consumeCPU(128);

 }


 @Benchmark

 public void consume_0256() {

  Blackhole.consumeCPU(256);

 }


 @Benchmark

 public void consume_0512() {

  Blackhole.consumeCPU(512);

 }


 @Benchmark

 public void consume_1024() {

  Blackhole.consumeCPU(1024);

 }


 /*

  * ============================== HOW TO RUN THIS TEST: ====================================

  *

  * Note the single token is just a few cycles, and the more tokens

  * you request, then more work is spent (almost linearly)

  *

  * You can run this test:

  *

  * a) Via the command line:

  *    $ mvn clean install

  *    $ java -jar target/benchmarks.jar JMHSample_21 -f 1

  *    (we requested single fork; there are also other options, see -h)

  *

  * b) Via the Java API:

  *    (see the JMH homepage for possible caveats when running from IDE:

  *      http://openjdk.java.net/projects/code-tools/jmh/)

  */


 public static void main(String[] args) throws RunnerException {

  Options opt = new OptionsBuilder()

          .include(JMHSample_21_ConsumeCPU.class.getSimpleName())

          .forks(1)

          .build();


  new Runner(opt).run();

 }
// 本例介绍了Blackhole的另一种用法，前面提到的Blackhole可以用来干掉“死码消除”，同时Blackhole也可以“吞噬”cpu时间片（怪不得起这个名字）
// Blackhole.consumeCPU的参数是时间片的tokens，和时间片成线性关系。

}